[rrd-users] adding DS values from multiple rrd files?

Simon Hobson linux at thehobsons.co.uk
Tue Aug 3 20:49:38 CEST 2010

At 13:48 +0000 3/8/10, Joel wrote:
>Thanks guys!
>I think the part I'm struggling with is how to define the CDEF for 
>the "total" variable inside a php foreach loop.  I get errors about 
>the CDEF being reused.
>Anyone out there doing rrdtool graphing with php?

I'm working in bash script, and piping the result of a load of echo 
statements through rrdtool, but the the same principal should apply. 
The actual code I've used is :
   for direction in in out
     for GraphIP in "${IPs[@]}"
       [ ${GraphIP} -eq ${IPs[0]} ] \
         && echo -n "        CDEF:data${direction}avg=${GraphIP}-${direction}" \
         || echo -n ",${GraphIP}-${direction},+"
     echo "

The end result is I send the following to rrdtool :


So I keep adding more and more terms to an RPN expression inside the 
loop. I vaguely recall it took me a long time to figure out stuff 
like this when I was first writing these graphs.

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
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